Human Factors of Automated Driving: Towards Predicting the Effects
of Authority Transitions on Traffic Flow Efficiency.
Silvia F. Varotto
1, Raymond G. Hoogendoorn
1, Bart van Arem
1, Serge P. Hoogendoorn
1 Abstract (272 words)Automated driving potentially has a significant impact on traffic flow efficiency. Automated vehicles which are able to show cooperative behaviour are expected to reduce congestion levels by increasing road capacity, by anticipating traffic conditions further downstream and also by accelerating the clearance of congestion.
Under certain traffic situations, drivers could prefer to disengage the automated system and transfer to a lower level of automation or are forced to switch off by the system (e.g. in case of sensor failure). These transfers between different levels of automation are defined as authority transitions and could significantly affect the longitudinal and lateral dynamics of vehicles.
Microscopic simulation software packages can be used to ex ante evaluate the impact of automated vehicles on traffic flow efficiency. Currently, mathematical models describing car following and lane changing behaviour do not account for authority transitions. In order to develop an adequate model of driving behaviour for automated vehicles including authority transitions, an empirically underpinned theoretical framework is needed where human factors are accounted for. Figure 1 presents the relationships existing between authority transitions, human factors and traffic flow conditions.
In the proposed research, this theoretical framework is the basis for the prediction of effects of automated driving on traffic flow efficiency. Firstly, empirical data from Field Operational Test and driving simulation experiments will be collected and analysed. Secondly, microscopic traffic flows models incorporating human factors will be developed: within this framework, transient manoeuvres and authority transitions will be investigated taking into account variations within and between drivers. Thirdly, the effects of different penetration rates of automated vehicles and different levels of automation on traffic flow efficiency will be discussed.
Key words: automation, authority transitions, human factors, microscopic modelling, traffic flow efficiency.
1
Department of Transport and Planning, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, The Netherlands.
Figure 1. Theoretical framework of relationships between authority transitions, human factors and traffic flow conditions.
Human factors Traffic flow characteristics Road design Sensors Systems Human Machine Interface Human driving behaviour Longitudinal and lateral dynamics Vehicle
Road and traffic flow conditions
Driver capabilities Environmental
conditions
Relationships that will be investigated. Relationships that will not be investigated.
Authority transitions
